2010年10月20日

Structure of RCC1 chromatin factor bound to the nucleosome core particle

Structure of RCC1 chromatin factor bound to the nucleosome core particle

Makde, R. D. et al. (2010) Nature 467: 562-567

 

The monomeric GTPase Ran regulates a variety of critical cellular functions, such as transport of macromolecules across the nuclear membrane, microtubule assembly, and assembly of the nuclear envelope.  A steep gradient of Ran-GTP is maintained across the nuclear membrane due to the asymmetric distribution of RanGAP, a GAP for Ran which is found in the cytosol and RCC1, the GEF for Ran, which is associated with chromatin in the nucleus.  Despite the fact that RCC1 is a critical regulator of Ran, little structural information is available about the interaction between RCC1 and chromatin, and indeed, about proteins that interact with chromatin in general.  Makde et al. have solved the structure of Drosophila RCC1 in complex with Xenopus histones and the Wisdom 601 DNA sequence using x-ray crystallography.  Importantly, this structure reveals how RCC1 interacts with histones, and a previously unknown interaction between RCC1 and the DNA component of the nucleosome is revealed.  Although a model of how the RCC1-nucleosome complex might interact with Ran is presented, further studies are required to fully understand how Ran interacts directly with the nucleosome in an RCC1-independent manner, and how the interaction between RCC1 and histones enhances RCC1's GEF activity.